THE SUBCLAVIAN REGION. 95 



trolled also, in many instances, by drawing the arm back- 

 wards, and forcibly depressing the tip of the shoulder. 



Dissection. After removing the skin, superficial fas- 

 cia, and the posterior fibres of the platysma, with the 

 thin fascia immediately beneath this, the handle of the 

 knife will be generally found sufficient to expose all the 

 important relations. The first structures met with, are 

 the descending superficial branches of the cervical 

 plexus (the acromial and clavicular), and a considerable 

 number of lymphatic glands. Beneath the layer of the 

 cervical fascia which covers in the space is a quantity of 

 loose cellular tissue and fat, in which lie lymphatics 

 and superficial cutaneous and glandular vessels. The 

 upper border of the omo-hyoid, inclosed in its sheath of 

 deep cervical fascia, is next met with, the anterior layer 

 binding down the subclavian vein against the clavicle, 

 which vein here receives the external jugular just be- 

 hind the attachment of the sterno-cleido-mastoid. Im- 

 mediately behind the vein, internally, is the anterior 

 scalene muscle; and emerging from behind it, and meet- 

 ing the vein at an acute angle in a plane superior to it, 

 is the subclavian artery ; and in a plane more posterior, 

 but above, are the cords of the brachial plexus. The 

 anterior scalene muscle is inserted into a tubercle (the 

 scalene tubercle) on the first rib, which is a guide to the 

 vessel, and in front of, and behind the tubercle are 

 grooves on the rib, in which lie, in the anterior, the sub- 

 clavian vein, and, in the posterior, the subclavian artery, 

 separated from each other by the muscle. The supra- 

 scapular artery, a branch of the subclavian in the first 

 part of its course (normally), with its vein, crosses the 

 main trunk just below the crossing of the omo-hyoid, 

 and lies along the upper border of the clavicle. The 



